Liquid fuel injection pumps for internal combustion engines



y 1958 F. M. EVANS 2,833,218

LIQUID FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Filed Dec. 14, 1954 Fig.1 Fig. 2

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g Y a d v u Izzy 4912120 0 United States Patent LIQUID FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Fraser Mackie Evans, Acton, London, England, assignor to C. A. V. Limited, Acton, London, England Application December 14, 1954, Serial No. 475,069

Claims priority, application Great Britain December 23, 1953 Claims. (Cl. 103-37) This invention relates to liquid fuel injection pumps for internal combustion engines, of the type comprising one or more reciprocatory plungers.

The object of the present invention is to provide a convenient device for enabling an extra supply of fuel to be given by the pump when starting the engine.

A device in accordance with the invention. comprises the combination with the working chamber associated with the plunger, or with one or each of the said chambers of a multi-plunger pump, of a variable-volume cavity containing a freely movable shuttle, a passage between the fuel inlet and the end of the cavity remote from the working chamber, and a valve for controlling the said passage.

[n the accompanying drawings,

Figure 1 is a sectional side elevationof a liquid fuel injection pump embodying the invention.

Figure 2 is a similar view to Figure l, but with the control valve and shuttle in different positions.

Figure 3 is a similar view to Figure 1 illustrating a modified feature.

Figure 4 is a fragmentary sectional side view illustrating another modified feature.

Figure 5 is a similar view to Figure 4 illustrating a further modification.

Figure 6 is a similar view to Figure 1 illustrating another form of liquid fuel injection pump embodying the invention.

Referring to Figure 1, the single plunger pump there shown comprises a body part a in which is formed a cylindrical bore for the plunger b, and in the body part is also formed an annular chamber 0 to which fuel is supplied by a feed pump, or by gravity from a feed tank. This chamber communicates withthe bore through ports d so situated that they are uncovered by the plunger when the latter is at the end of its suction stroke. A discharge passage e is provided in the end of the bore remote from the said ports and is controlled by a spring-loaded non-return valve The part g of theb ore between the inner end of the plunger and the discharge passage is hereinafter referred to as the working chamber. Reciprocation of the plunger is effected by an conventional means (not shown).

In one manner of applying the present invention to such a pump there is formed adjacent to the discharge end of the working chamber g a laterally-extending cylindrical cavity h which at one end is open to the said chamber. The other end communicates with the feed chamber by way of a passage i which may include a restricted orifice. In the said cavity h is contained a freely movable shuttle the movement of which serves to vary the volume of the part of the cavity which is open to the working chamber. Movement of the shuttle towards the working chamber is limited by a flange k on the end of the shuttle adjacent to the said passage 1'. If it is desired to vary the extent of travel of the shuttle in the direction away from the working chamber, an adjustable stop k may be provided.

end of the passage. operable push button 0 acting on a spring p placed be- 2,833,218 Patented May 6, 1958 The passage leading to the feed chamber 0 is controlled by a valve. In the example shown in Figure 1 this valve comprises a cylindrical plug m having a conical end adapted to co-operate with a seating n at the exit The plug is movable by'a manually tween it and the plug.

, The arrangement is such that during normal working conditions, the reciprocatory plunger b after closing the ini let ports d causes the liquid fuel to be displaced from the Working chamber into the variable height volume cavity before liquid is discharged through the'non-return valve 1 so causing the shuttle to move and return a corresponding volume of liquid fuel from the other end of the cavity to the feed chamber, the control valve m being open. During the suction stroke of the plunger the shuttle returns to its initial position. Consequently during normal conditions the displacement of fuel to and from the variable volume cavity hasno effect on the normal pump output, and the latter is only variable by the usual pump governing means.

When an extra supply of fuel is required, as when' amount'equal to that which under normal conditions is accommodated in the variable volume cavity h.

In the modification shown in Figure 3, the control I valve m is normally closed by the spring p and is adapted to be opened automatically by pressure of, the fuel supplied by a feed pump to the feed chamber 0, the valve 1 having formed on it a piston-like part m of larger diameter than the end which co-operates with the seating 21. In this case the feed pump is driven by the engine and is adapted to supply fuel at a pressure which increases with engine speed. Under normal working conditions the feed pressure holds the valve open. But at slow speeds, such as occur when the engine is being started,

the valve is held closed by its associated spring p.

As above mentioned, a restricted orifice may be arranged in the passage i leading to the supply chamber. An example is shown in Figure 4, where the restricted orifice is indicated by r, the valve In in this example being similar to that shown in Figure 1. Alternatively and when an automatically operable control valve is used, as shown in Figure 3, the valve in may be adapted to form the restricted orifice as shown in Figure 5. In this example, the passage i is enlarged adjacent to the seating n, and an extension s on the valve m which extends through the seating n is shaped to vary the orifice in the said seating so that under increasing fluid pressures acting on the part m the orifice in the seating is progressively diminished, also at low pressures the orifice is closed.

An advantage obtained by providing a fixed or a variable restricted orifice in the passage i is that when the 7 engine is in action the rate at which the fuel in the said passage can flow when the shuttle is moved is progressively diminished with increasing speed of the engine. The extent of movement of the shuttle at high engine speeds is therefore less than at low speeds and the amount of fuel suppiled by the pump to the engine progressively increases with increase of speed. Consequently the shuttle can thus serve not only to provide a temporary increase of fuel to the engine when starting but also effect a progressive increase of rate of fuel supply with increasing engine speed.

Another form of fuel pump to which the invention is applicable is shown in Figure 6, and comprises a rotary member :3, herein referred to as a distributor, contained in a cylindrical bore in the body part a of the 2, 3, 4 and 5, and the fuel is discharged along the passage 5 to a radialpassage 6 which by rotation of the distributor establishes communication with each in turn of a plurality of outlet passages 7 in the body part. The rate of supply of fuel from the rotary feed pump x to the working chamber u'between the plungers v maybe regulated by an adjustable plug 8.

In one manner applying the invention to the pump shown in Figure 6, a cavity 11 of variable volume and 7 containing the shuttle jis located at the end of the axial passage 5 adjacent tothe said radial discharge passage 6 in the distributor t. Behind the said cavity h is formed a cavity 9 in communication with the fuel inlet passage 2 under the control of a valve m This valve may be similarto that shown in Figure 1, in which case it is operable by a push button. Or (and as shown) it may be similar. to that shown in Figure 3. The extent of movement of the shuttle is variable by an adjustable stop k i The, invention is not, however, limited to the examples above described, as it may be applied in like manner to other forms of reciprocatory plunger fuel pumps, and when applied to a multi-plunger pump of the'kind shown in Figures 1 and 3, one or each of the working chambers may be provided with a variable volume cavity and shuttle. When each of the working chambers is so provided, all the passages as i lead to a common fuel inlet through a single valve as m which may be manually or automatically operable as described.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel injection pump comprising in combination a body part having therein a working chamber and a variable-volume cavity open at one end to said working chamber, a reciprocatory plunger slidable in said working chamber, afuel inlet which communicates with and serves to admit fuel to said working chamber when said plunger is at one end of its stroke, a fuel outlet which communicates at one end with said working chamber and through which fuel admitted to said Working chamber from said inlet is dischargable by saidplunger, a shuttle freely slidable in said cavity in response to the pressure in said working chamber, and means including a control valve situated between said inlet and the end of said cavity remote from said working chamber for exposing the corresponding ,end of said shuttle to fuel from said inlet so that reciprocation of said plunger is accompanied by reciprocation of said shuttle only when said valve is open.

2. A liquid fuel injection pump according to claim 1, in which said valve is provided with a manually operable member whereby saidvalve can be held in its closed position.

3. A liquid fuel injection pump according to claim 1 in which said valve is provided with a loading spring tending to close said valve, and with a piston-like part through the medium of which said loading spring acts on said valve, said piston-like part being exposed at one end to the interior of said inlet so that the fuel pressure at said inlet tends to open said valve against the action of said loading spring. I

4. A liquid fuel injection pump according to claim 1,

, in which said means also includes a passage which communicates with said inlet, and through which fuel from said inlet has access under the control of said valve to the end of said shuttle remote from said working chamher, said passage having therein a fixed restriction.

5. A liquid fuel injection pump according to claim 1, in which said means also includes a passage which communicates with said inlet, and through which fuel from said inlet has access under the control of said valve to the end of said shuttle remote from said working chamher, said valve and passage having adjacent parts shaped to form in said passage a restriction which is variable by movement of said valve.

Hurst Sept. 29 1936 Voit Mar. 27, 1956 

